Numerous types of dispensers for flexible sheet material wound on cores, such as rolls of paper towels, are known in the prior art. The core on which the flexible sheet material is wound typically has supporting spindles extending beyond the ends of the rolls. The spindles are used to support the roll in, and guide it through, the dispenser. Prior art dispensers frequently use a dispensing or feed mechanism, generally comprising a plurality of rollers, to feed the sheet material out of the dispenser. Such dispensing mechanisms have included a cutter which cuts a preselected length of the sheet material being dispensed. In typical prior art dispensers, the roll surface of the dispensing roll has rested on one of the rollers of the dispensing mechanism. Thus, whenever sheet material is advanced through the dispensing mechanism, the dispensing roll is rotated by virtue of its contact with a roller of the dispensing mechanism.
One type of prior art dispenser is a multiple roll dispenser wherein a first roll, from which the sheet material is being dispensed, is automatically moved to a temporary storage position when nearly depleted and a second reserve roll is moved into a dispensing position. U.S. Pat. No. 4,236,679 to Jespersen, discloses both a single roll and a multiple roll dispenser. In the multiple roll dispenser, the remaining sheet material on a first dispensing roll, after its core has dropped to a core storage position, is used to rotate a second reserve roll to thread the sheet material from the reserve roll through the dispensing mechanism. The automatic initiation of dispensing from the second reserve roll is important to the convenience of use of multiple roll dispensers.
The roll surface of the dispensing roll in the multiple roll dispenser disclosed in the '679 patent rests on the feed roller of the dispensing mechanism. Likewise, after the dispensing roll has dropped to a storage position, the reserve roll is lowered and placed in direct contact with the feed roller of the dispensing mechanism through contact with the remaining length of sheet material on the dispensing roll in order to thread the leading edge of the sheet material from the reserve roll through the dispensing mechanism. U.S. Pat. No. 4,307,639 to DeLuca et al. similarly discloses a multiple roll dispenser in which the dispensing roll, as well as the reserve roll after it has dropped into the dispensing position, rest on one of the rollers of the dispensing mechanism. Specifically, the roll rests both on a feed roller and, for a period of time, on a pressure roller of the dispensing mechanism. U.S. Pat. No. 4,307,638 to DeLuca et al. also discloses a multiple roll dispenser wherein the roll surface of the roll from which sheet material is being dispensed rests on one of the rollers of the dispensing or feed mechanisms. In the dispenser disclosed in the '638 patent, the roll rests on a pinch roller of the dispensing mechanism, rather than the primary feed roller.
The technique of placing the roll surface of the roll from which sheet material is being dispensed in direct contact with a roller of the dispensing mechanism is a convenient way to initiate dispensing from a reserve roll which has dropped to a dispensing position in a multiple roll dispenser. However, the direct contact between the dispensing roll and a roller of the dispensing mechanism can cause jamming problems. First, there is no fixed location in such prior art mechanisms for the center of the core of the dispensing roll. Since the roll surface must remain in contact with the roller of the dispensing mechanism, the rotation axis must continuously change as the diameter of the roll diminishes. Thus, no mechanism is provided to ensure that the axis of the core remains parallel to the roller on which the dispensing roll rests. If soft-wound rolls of sheet material are used, one end of the core can rise above or fall below the other end of the core causing the sheet material to travel to one side as it is withdrawn. Such uneven dispensing of the sheet material eventually jams the feed mechanism. Second, if the dispensing roll is rapidly rotated and then brought to a sudden stop, over spinning will occur. While braking mechanisms have been incorporated into prior art dispensers to reduce overspin, it generally can not be completely stopped. If the dispensing roll rests directly on one of the rollers of the feed mechanism, it will jump forward of the roll at each sudden stop, creating an unraveled loop of loose sheet material in the dispensing mechanism adjacent the roller. The size of this loop increases with each use of the dispenser, since the roll of sheet material rotates together with the rollers of the dispensing mechanism. Again the dispensing mechanism eventually jams.
A device and technique was thus needed to reliably initiate the feeding of sheet material through a dispensing mechanism from a roll that is lowered from a reserve to a dispensing position while reducing the likelihood of jamming of the dispensing mechanism. The present invention was developed to accomplish this objective.